The iPhone 6 and 6 Plus incorporated what were arguably the most significant upgrades Apple's smartphone had ever seen. In addition to much larger screens, the iPhone 6 models also introduced to Apple Pay, Cupertino's take on mobile payments.

Not surprisingly, iPhone 6 sales have been record-setting, which of course leads one to wonder what Apple has planned in order keep its iPhone sales momentum going strong.

Well, thanks to KGI Securities analyst Ming-Chi Kuo, we now know a whole lot more about what type of new features we can expect to see in Apple's next-gen iPhone models.

One of the more exciting things about Apple's upcoming iPhones, according to Kuo, and originally relayed by GforGames, is that they will finally come with 2GB of RAM. With more RAM in tow, next-gen iPhones will likely run a bit smoother, a bit faster, and will be able to handle more intensive apps.

Kuo also reveals that Apple's upcoming iPhone 6s models will be powered by a next-gen A9 processor. This tidbit shouldn't come as too much of a surprise given that Apple has continuously enhanced the iPhone's processor each and every year.

Some other new features to look forward to include a stronger caliber of aluminum for the device's casing. While it's unclear if this was Apple's plan all along, some are speculating that Apple is making the iPhone frame more durable due to the overblown controversy that was bendgate. Also on the agenda is an improved 12 megapixel camera. It's worth noting, though, that camera quality isn't solely a function of megapixels. To that end, expect to see Apple really up the ante in terms of photographic performance with some additional software tweaks.

As if that weren't enough, Kuo also writes that Apple's next-gen iPhone models will feature Force Touch functionality, similar to what Apple has implemented on the Apple Watch and the recently released MacBook. It remains to be seen how Force Touch might be implemented on the iPhone, but it certainly presents some intriguing use-case scenarios. Intriguingly, Kuo writes that Force Touch may be positioned as the iPhone's most attractive feature.

Touch ID will reportedly be getting an upgrade as well. Echoing similar reports from earlier in the year, Kuo relays that Touch ID will be both quicker and more reliable on account of enhanced Touch ID sensors.

Now, if you remember the run-up to the iPhone 6, you might also remember the bevy of rumors surrounding sapphire displays. At the time, it was largely assumed that Apple, thanks to its partnership with GT Advanced Technologies, was going to release a scratch-proof smartphone with a sapphire display. But as it turned out, GT Advanced Technologies filed for bankruptcy after failing to meet some of Apple's stringent testing requirements. Well, sapphire displays may be back on the agenda for this upcoming release cycle. To that end, Kuo writes that there may be a limited edition model of the iPhone 6s with a sapphire display. If this is in fact the case, expect Apple to charge a bit of a premium for it. Some believe that Apple may gauge the interest in such a device in order to determine if its entire iPhone lineup should get the sapphire treatment in the future.

GforGames adds:

More interestingly is that the report claims that if certain yield issues will be overcome, the 5.5-inch iPhone 6s Plus might come with a sapphire covered display. Almost all hope for a sapphire display on an iPhone has been lost last year when Apple’s supplier, GT Advanced, went bankrupt. One source that relied KGI's report says that Apple plans for a Limited iPhone 6s Plus edition with a sapphire display as opposed to the new material being applied to the whole 6s Plus line.

And finally, Kuo relays that Apple this September may introduce a new Rose Gold color option for the iPhone.

All things considered, it looks as if Apple's next-gen iPhone will provide a compelling upgrade opportunity for existing iPhone owners. While there may not be an overwhelming "must-have" feature, all of the incremental upgrades, taken together, are certainly compelling.

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Yoni Heisler is a technology writer and Mac nerd who's been using Apple products for well over 21 years. He actively covers a wide variety of Apple topics, from legal news and rumors to current events and even Apple related comedy and history.